Study for Liquid-Liquid Extraction of Gadolinium (III) Ion using New Azo Derivative and Its Thermodynamic Functions

Abstract

Colored azo compounds can be considered one of the most widely used chemicals, as they have many applications in colorful plastics and polymers, pharmaceutical, printing, food, cosmetic, and biomedical industries, as well as for advanced organic synthesis applications. This work aims to prepare and characterize a new azo compound and use it in the process of separating one of the rare earth elements, the element gadolinium.so that the study contains two processes, The first process includes the synthesis a new azo derivative called 3-(4-(dimethylamino)phenyl) diazenyl)-2-hydroxy-5-sulfobenzoic acid (DPDBA)  from diazonium salt pairs of  (N1,N1-dimethylbenzene-1,4-diamine dihydrochloride) with  2-hydroxy-5-sulfobenzoic acid dihydrate , The reagent chemical formula (C15H15N3O6S) and the molecular weight was (365.36 g/mol)  , The reagent powder has greenish color , The pure reagent melting point is ( 183-185 °C), the reagent characterizes by many spectroscopic methods  (UV-Vis., FT-IR, 1HNMR, Mass spectrum and 13CNMR) .The second process was used  the new azo as reagent to separate the gadolinium (III) ion by a solvent extraction process , Effect of the various parameters on the extraction process this is done by calculating (D & %E). The best pH was (2) , The best period time for equilibrium was (20) minute, Chloroform was the best solvent for the extraction .The results also showed that (D) and (%E) values increase with the (DPDBA) reagent concentration increase as well as with the increase of Gd(III)  concentration increase , Investigating the role temperature on the extraction, and calculating the thermodynamic  function (∆Hex, ∆Gex ,∆Sex), The chelating ratio of metal to ligand also determined by Job's and mole ratio techniques, was found to be (1:3) M:L.